Abstract
PURPOSE: To evaluate the impact of an optimized online adaptive radiation therapy workflow on physician involvement. METHODS AND MATERIALS: Data from a prospective phase 2 trial involving 34 prostate cancer patients treated with cone beam computed tomography (CBCT)-based online adaptive radiation therapy (62 Gy in 20 fractions) were analyzed. Manual interventions were required for 2 steps in the workflow: radiation therapy technologist review and adjustment of automatically segmented organs, guiding target segmentation, so-called "influencer," while physicians reviewed and refined the targets. Three different workflows were compared: 2-influencer (rectum and bladder), 3-influencer (+prostate), and 5-influencer (+seminal vesicles and bowel). Time for workflow steps, extent of manual corrections, and target volume changes were compared. RESULTS: A total of 613 fractions were analyzed. The 5-influencer workflow reduced manual target corrections to 11% of fractions compared with 51% for the 3-influencer workflow and 61% for the 2-influencer workflow (P < .001). Median session duration across workflows was 24.0 minutes (IQR, 22.0-28.0). Median target review times were shortest with the 5-influencer workflow at 2.5 minutes compared with 5.0 minutes for the 3-influencer workflow (P < .001) and 5.6 minutes for the 2-influencer workflow (P = .002). Most patients (84%) found the treatment time well tolerable. CONCLUSIONS: This study of prostate cancer patients suggests that optimized workflow reduces the need for physician involvement in online CBCT guided adaptive radiation therapy. Optimized workflows may facilitate a more radiation therapy technologist-driven approach similar to standard image guided radiation therapy. Further studies in other cancers, also focusing on clinical endpoints, are needed to further improve CBCT guided online adaptive radiation therapy.